Ariston awd 1200 fills,advances and empties, but will not wash or spin.Belt ok, drum rotates free. Any advise?

There are many reasons that this could be noisy...

When you turn the drum (quickly) when it's empty does it rumble? Bearings, drum support or motor bearings.

If it sounds like a pneumatic drill when filled and spinning it could be drum support, bearings, balance weight or suspension.

These are not an exhaustive list but the usual suspects.

Remove the rear cover and check the drive belt has not come off.
If the belt is off, there should be no resistance to turning drum, if there is, then there could be something trapped inside, or the main drum bearings could be failing.

Could be anything , from a loose connection or broken wire to a control board or timer fault..You say the brushes are o/k, but if they are less than 3 or 4mm long, they need replacing.
Even the motor itself could be faulty.
I assume the drive belt is o/k, and correctly tensioned..
It is difficult to advise you further because thier are too many variables involved.
Please leave your comments on my suggested solution.
Thankyou.

open rear cover , see if belt slips. then remove belt and rotate empty drum if its jam than drum bearings need to change. if drum is free then belt might be loose and needs replacement.

Check lid switch.

If you have wash action from then the motor is most likely O.K.

If your lid switch is faulty, the machine stops before the spin cycle.

Ash

if it fill with water then stops it is the ellement the machine first fills turns the drum then heats up the thermostat cuts in and the it emptys rinses and spins so if it does not get to temp it will stop or continue to wash forever

If the belt and the motor are OK, then tell your friend to check the motor coupler, the MCU (motor control unit).

See also the following link : It doesn't spin.

the carbon dust that you mention ? on the drivebelt will//may have come from the electric motor carbon brushes especially as you sy machine is 4 yrs old you can diy inspect the brushes by removing the rear panel to access motor unplug the socket from motor then slacken belt and remove belt from pully remove the motor you will see location f brushes x2 opposit each other and normally held in position ont armature of motor by coiled pressure clip like watch spring and brush has wire embedded in it and other end a push on terminal? when these brushes wear down normally the fist indication is fast spin slows then eventually no rotation of drum? over a period of time? SO easy diy to renew brushes if as above worne down /not contacting armature? cost approx £5 here in n/west uk worth investigating and diy saving ££££s $$$$s? and i hope you have good luck hope this helps/inspires you?

Usually there are two windings for washers, One goes forward and one reverse, either one is bad OR: There is also a transmission in washers that when washing; they agitate the load when spinning; they, well spin! (ha) If it wont wash then there is either an internal component in the tranny bad or a solonoid that has gone out. Take the cover off and check to see if the belt is ok as well. Let us know :-)

I HAD THE SAME PROBLEM ON A 4 MONTH OLD MACHINE AND I CALLED A SERVICE PERSON. HE SAID THAT I CAN THROW IT AWAY. THIS IS A PROBLEM THAT NOBODY CAN FIX.